This invention relates to thermosyphon radiators.
Thermosyphon radiators are the type in which a vaporising liquid contained within a sealed panel is heated, in use, by a heated pipe extending with clearance through the lowermost part of the panel. The liquid is vaporised and travels upwardly to the colder upper parts of the radiator where the vapour condenses giving out its latent heat of vaporisation into the radiator surface which is then convected to the air in a space, e.g. a room.
In one such type of radiator described in UK Patent No. 2099980B, the heating pipe is provided with a wick means in the form of a metal gauze depending therefrom, the pipe itself lying wholly above the level of a reservoir of the liquid. The wick dips into the liquid and continuously supplies a thin film of the liquid around the pipe for evaporation by the heated pipe to the upper parts of the radiator where the vapour condenses to give out its latent heat of evaporation to the radiator surface. The condensed liquid then trickles down the inside of the radiator and returns to its reservoir.
One problem with this type of system is that it is necessary to provide a wick to impart the necessary capillary action to draw the liquid up to the pipe increasing the cost of system. It is therefore an object of the present invention to provide a thermosyphon radiator without a wick.
According to one aspect of the present invention, we provide a thermosyphon radiator comprising a sealed panel containing a reservoir of vaporising liquid in a lowermost part of the panel and a heating member extending with clearance through the lowermost part of the panel, the member being at least partially immersed in the vaporising liquid.
The vaporising liquid may be water, but ammonia, methanol or acetone are viable alternatives.
According to another aspect of the present invention we provide a thermosyphon radiator comprising a sealed panel containing water in a lowermost part of the panel and a heating member extending with clearance through the lowermost part of the panel.
Preferably the member is a pipe for carrying a second liquid. Suitably the pipe is covered externally with a fine metallic mesh, compacted metallic wool, fibrous material or a polymeric coating. Alternatively the pipe can be coated with a porous material such as a sintered metallic or ceramic material.
Conveniently the pipe is immersed in the vaporising fluid, e.g. water to a depth of no less than three-quarters of the diameter of the pipe.
The panel may be of roll-bonded aluminium, which may be pretreated to inhibit corrosion.
The panel may be hermetically sealed and preferably is evacuated except for the vaporising liquid.
The radiator may be externally finned to increase the heat transfer to the space to be heated.
Suitably the water is distilled water and may contain corrosion inhibitors.